Heat flow sensors and measurements are widely used in medicine, building and agriculture, as described in U.S. Pats. Nos. 4,274,475; 5,524,618; 5,803,915; 6,533,731; 6,595,929 and 7,232,255 and in articles: Heat Flow Sensors, Bulletin 36614, Rdf Corporation. Hudson, N.H., USA; Degenne, M., Klarsfeld, S., in: Building Applications of Heat Flux Transducers, ASTM STP 885, Bales, E., Bomberg, M., Gourville, G. E. (eds.); Philadelfia: American Society for Testing and Materials, 1985, pp 163-171; Heat Flow Sensors by F. van der Graff, VCH Verlagsgesellschaft mbh, D-6940 Weinheim Federal Republic of Germany.
There are known constructions of heat flow sensors with openings for the passage of air using various thermo sensitive elements—resistance thermometer, thermocouple, thermistors, thermo diodes and etc.
Thermo sensitive elements are consequentially located in columns between series of openings, and thus are protected from damage by stickers or paint.
However since there is unused space between those openings, the sensitivity per unit area is a serious limitation in medical measurements.